1. Field of the Invention
The present invention relates generally to memory devices, and more particularly to memory devices having shock force protection.
2. Description of the Related Art
Previously, an optical head carriage that uses a linear motor system has been set up to move in a completely free manner along the top of a guide rail, and for this reason, there has been cause for concern with regard to damage that may occur to the lens actuator and carriage in cases where a shock is received during transport.
In order to make improvements regarding this point, a carriage lock mechanism has been installed for the purpose of operating a stopper which a portion of the carriage would strike against when a disk is not installed. Specifically, Japanese publication patent numbers H08-096530 and H05-282692 call for the use of an electric motor or electromagnet to move the carriage lock immediately before non-access or cut-off of electrical power occurs, the carriage lock being cancelled during operation startup.
However, due to designs that result in smaller and lighter devices, there is not enough space to allow for the installation of these kinds of motors and electromagnets. Since there is a need to operate the carriage as well as the locking mechanism, it is difficult to maintain enough electricity in the case of low-consumption devices and battery powered devices, particularly for shut down purposes.
Furthermore, Japanese publication patent numbers H05-303844 and 2000-276873 call for a mechanical link between the carriage lock and the disk loading mechanism or the eject mechanism. The link to the disk loading operation cancels the carriage lock, and the link to the disk ejection operation calls for a carriage locking mechanism to operate the carriage lock.
However, due to competitive pressure to reduce cost and the number of parts that has been seen in the industry recently, there is a trend toward eliminating the carriage lock mechanism. At the very least, though, there is a need to prevent contact between the objective lens and the memory medium, and as called for in Japanese patent application number 2000-161844, a regulating member 64a in the form of a mechanical stopper is installed for the purpose of regulating contact between the memory medium and the objective lens, which is supported by a leaf spring.
Recently, 3.5-inch magneto optical disks have achieved a memory capacity of up to 2.3 GB, and with their high-density recording capability, there has been a need for smaller recording marks as well as the formation of recording pits. For this reason, there is a trend toward a smaller laser light beam diameter as well as high NA (numerical aperture), making it necessary to have a closer distance between the optical disk and the objective lens.
However, if the gap (space) between the objective lens and the medium becomes smaller than the amount of surface deflection of the memory medium, a problem will arise in that it will become impossible from the standpoint of space to use the type of mechanical stopper indicated as the regulating member 64a in Japanese patent application number 2000-161844. Furthermore, in the case of the carriage lock mechanisms noted in Japanese publication patent numbers H05-303844 and 2000-276873, the carriage lock operation is cancelled while a disk is loaded, such that when a vibration occurs due to the portability of the optical disk device, or when the optical disk device is dropped while an optical disk is inserted within the device, it becomes impossible to lock the carriage in its specified position. This situation poses the problem of damage not only to the carriage and lens actuator, but also to the disk.
Accordingly, one object of this invention is to present a carriage lock mechanism as well as a memory device that uses such a mechanism, wherein it is possible to prevent the carriage from shifting from its specified position, regardless of whether or not a memory medium is loaded, as a result of the capability to provide a relevant response to the occurrence of shock.